<div class="node_panel">
  <el-button round size="small" v-for="item in nodeList" :key="item.text" @mousedown="$_dragNode(item)">
    <div class="node-item-icon" :class="item.class">
    </div>
    <span class="node-label">{{item.text}}</span>
  </el-button>
</div>